1. Field of the Invention
This invention relates to an apparatus and method for thermal processing that is performed in the manufacturing process of a semiconductor device, and more particularly to an apparatus and method for thermal processing that performs thermal processing of a semiconductor wafer at high speed in a single-wafer process.
2. Description of the Related Art
In recent years, as the dimensions of the element patterns of semiconductor integrated circuit devices (hereafter referred to as semiconductor devices) have become more minute, thermal processing has shifted from long anneal processing, in which batch-type thermal processing is performed in a diffusion furnace over a long period of time, to RTP (Rapid Thermal Process) technology, in which thermal processing is performed in a short period of time of about 10 seconds in a single-wafer process. The application of this RTP technology is particularly advancing in the area of thermal activation processing that is performed after the impurity doping when forming a shallow junction on the semiconductor substrate. A lamp-type RTP apparatus, which controls the raising and lowering of the substrate temperature by adjusting the radiated energy (electromagnetic waves) that is radiated from a substrate heating lamp such as a halogen lamp, is currently being developed and is becoming wide spread as this kind of apparatus.
However, in this RTP technology, since the thermal processing time is extremely short, it is difficult to the make the substrate temperature during thermal processing uniform over the entire surface, and to match the substrate temperature with the desired thermal processing temperature. As a countermeasure against this, in a conventional lamp-type RTP apparatus, construction is employed, for example, in which both the top surface and bottom surface of the wafer are heated by a lamp, or construction is employed in which the actual wafer temperature during thermal processing is measured by a temperature sensor such as a thermocouple, and control for raising or lowering the substrate temperature is performed based on feedback of that temperature.
FIG. 5 shows the typical construction of a conventional lamp-type RTP apparatus 100. In this lamp-type RTP apparatus 100 there is a plurality of both top lamps 102 and bottom lamps 105, which are arranged at the top and bottom inside a chamber 101 in which thermal processing is performed, and they are used for heating a wafer 103. The number and arrangement of the lamps 102, 105 are optimized such that the temperature is uniformly distributed over the entire surface of the wafer 103.
Moreover, the temperature of the wafer 103 that is placed between the top lamps 102 and the bottom lamps 105 inside the chamber 101 is adjusted by controlling the electric power that is input to the top lamps 102 and the bottom lamps 105. At this time, the temperature of the wafer 103 during thermal processing is measured by a thermocouple 104 that comes in contact with the rear surface of the wafer 103, and that temperature is used in temperature-feedback control.
When the light of the heating lamp includes wavelengths between 900 to 1200 nm, and thermal processing is performed with a circuit pattern formed on the wafer 103, the transmission rate of the aforementioned wavelength of the incident light on the surface of the wafer 103 varies depending on the area and arrangement of this pattern, thus it becomes impossible to accurately measure the temperature with a thermocouple. Therefore, in current lamp-type RTP apparatuses, a pyrometer, which measures the intensity of the electromagnetic waves (infrared rays) that are radiated from the wafer without direct contact, is used as the temperature sensor instead of a thermocouple, making it possible to stably measure the substrate temperature regardless of the state of the wafer.
Also, in some lamp-type RTP apparatuses, a method is used for improving the uniformity of the temperature on the surface of the wafer 103 in which the intensity of the electromagnetic waves incident on the surface of the wafer is averaged by rotating the wafer 103 at high speed during heating.